Apparatus for intermittently transporting stacks of paper sheets or the like

Abstract

An apparatus for transporting several files of spaced-apart stacks of paper sheets has several transporting units, one for each file of stacks, and each such transporting unit has three endless toothed belts which are installed in a frame in parallel vertical planes and carry outwardly extending lobes. The lobes on the two outer belts of a unit engage the rear edge faces and the lobes on the median belt of each unit engage the front edge faces of stacks in the respective files. Each belt is trained over two toothed pulleys and one pulley of each outer belt is driven by a first shaft whereas one pulley of each centrally located belt is driven by a second shaft. The second shaft is driven directly by a stepping motor, and the first shaft is driven by the stepping motor through the medium of a transmission which alternately increases and reduces the speed of the first shaft relative to the second shaft so that the lobes on the outer belts of each unit move away from the lobes of the centrally located belts, while the respective transporting units are in the process of receiving fresh stacks or discharging stacks, to thus ensure that the lobes cannot deface or otherwise damage the sheets of the stacks and that the stacks can be properly transferred onto the respective transporting units even if they are not delivered thereto at regular intervals.

I claim: 
     
       1. Apparatus for stepwise transport of at least one file of discrete commodities in a predetermined direction and along a predetermined path, particularly for transporting stacks of paper sheets or the like, comprising at least one transporting unit including more than two endless parallel conveyors each having at least one projection arranged to extend into and from said path in response to movement of the respective conveyor in said direction, said conveyors including a first group having at least one conveyor whose projection is located ahead of and a second group having at least one conveyor whose projection is located behind a commodity in said path, said unit further including discrete first and second rotary elements for each of said conveyors and each of said conveyors being trained over the respective rotary elements; and common drive means for said conveyors including a first shaft arranged to drive via first drive transmitting means one rotary element for each conveyor of said first group, a second shaft arranged to drive via second drive transmitting means one rotary element for each conveyor of said second group, stepping motor means arranged to intermittently rotate said shafts, and transmission means interposed between said motor means and said shafts, said transmission means including means for intermittently changing the angular position of one of said shafts with reference to the other of said shafts to thereby change the spacing between the projection of each conveyor in one of said groups and the projection of each conveyor in the other of said groups so that the spacing is larger as said projections receive or discharge said commodities and the spacing is smaller during conveyance of said commodities between the reception or discharge zones at which the commodities are received by or discharged from between said projections. 
     
     
       2. The apparatus of claim 1, wherein one of said groups includes a pair of conveyors and the other of said groups includes a conveyor disposed between the conveyors of said pair. 
     
     
       3. The apparatus of claim 1, wherein said one shaft is arranged to drive one rotary element for each conveyor of said second group. 
     
     
       4. The apparatus of claim 1, wherein said means for intermittently changing the angular position of said one shaft includes means for accelerating said one shaft with reference to said other shaft. 
     
     
       5. The apparatus of claim 1, wherein said means for intermittently changing the angular position of said one shaft includes means for decelerating said one shaft with reference to said other shaft. 
     
     
       6. The apparatus of claim 1, wherein said means for intermittently changing the angular position of said one shaft comprises means for alternatively accelerating and decelerating said one shaft with reference to said other shaft. 
     
     
       7. The apparatus of claim 1, wherein said transmission is operative to change the angular position of said one shaft with reference to said other shaft during the intervals of idleness of said motor means between successive rotations of said shafts. 
     
     
       8. The apparatus of claim 1, further comprising common prime mover means for said motor means and said transmission means. 
     
     
       9. The apparatus of claim 1, wherein said transmission means further comprises an endless flexible element trained over said shafts and having first and second reaches, said means for changing the angular position of said one shaft comprising first loop forming means engaging one of said reaches, second loop forming means engaging the other of said reaches, and means for simultaneously shifting said loop forming means with reference to said flexible element so that the dimensions of the loop which is formed in the one reach by said first loop forming means increase proportionally with attendant reduction of the dimensions of the loop which is formed in the other reach by said second loop forming means or vice versa and said one shaft is rotated by said flexible element relative to said other shaft when the dimensions of said loops change. 
     
     
       10. The apparatus of claim 9, wherein said flexible element is a toothed belt and said shafts comprise pulleys for said belt. 
     
     
       11. The apparatus of claim 9, wherein said loop forming means include dancer rolls and said shifting means includes common holder means for said rolls. 
     
     
       12. The apparatus of claim 9, further comprising first and second guide members flanking one of said loop forming means, said flexible element being trained over said guide members. 
     
     
       13. The apparatus of claim 12, wherein said guide members are rotatable about fixed axes. 
     
     
       14. The apparatus of claim 9, wherein said shifting means comprises a pivotable lever and cam-and-follower means for pivoting said lever back and forth. 
     
     
       15. The apparatus of claim 1, wherein said drive means further comprises means for transmitting torque from said motor means to said other shaft, said means for intermittently changing the angular position of said one shaft comprising means for rotating said one shaft in response to rotation of said other shaft. 
     
     
       16. The apparatus of claim 1, wherein said transmission means includes means for changing the angular position of said other shaft with reference to said one shaft. 
     
     
       17. The apparatus of claim 1, further comprising means for changing the angular position of one of said shafts with reference to said motor means and said transmission means. 
     
     
       18. The apparatus of claim 1, wherein said conveyors include toothed belts. 
     
     
       19. The apparatus of claim 18, wherein said projections are lobes which are secured to the respective belts.